Objective To describe the disease characteristics of patients with juvenile idiopathic arthritis (JIA) included in an inception cohort, to analyse how many patients from each JIA category reach an inactive disease state within the first year of specialised care and to determine predictors for attaining inactive disease.

Methods Patients with JIA were enrolled in this study at 11 large German paediatric rheumatology units within the first 12 months after diagnosis. Laboratory and clinical parameters such as JIA core criteria and data on the medication used were collected every 3 months. Non-parametric statistical testing was performed for the comparison of the JIA core criteria at follow-up. Generalised linear models were used to analyse differences in the rates at which inactive disease was reached and to determine potential predictors.

Results Of the 695 patients with JIA included in this analysis, approximately 75% experienced a period of inactive disease under treatment with disease-modifying antirheumatic drugs and systemic steroids in most cases with systemic-onset JIA or polyarthritis at least once during the first 12 months in ICON. Significant improvements were observed in all JIA core criteria, in disease activity and in functional status from baseline to the 12-month follow-up. Younger age at onset, a shorter duration between symptom onset and diagnosis and a positive antinuclear antibody status increased the probability of attaining an inactive disease state.

Conclusions The 12-month outcome of JIA was good under real-life conditions, with half of the patients having attained inactive disease with contemporary treatments. Since a short duration between symptom onset and diagnosis was correlated to a period of inactive disease, children suspected of having JIA should be transferred to specialised care as soon as possible.